I have wondered why some authors claim that people rarely if ever change their mind. I have changed my mind many times. This could be because I have weak character, because I have no self-defining philosophy, or because I like change. Whatever the reason, I enjoy changing my mind. I have occasionally irritated colleagues with my seeming motto of 'If it ain't broke, break it.'

At the same time, I adhered to a value common in the day-to-day business of scientific research, namely, that changing one's mind is alright for little matters but is suspect when it comes to big questions. Take a theory that is compatible with either conclusion 'x' or conclusion 'y'. First you believed 'x'. Then you received new information and you believed 'y'. This is a little change. And it is a natural form of learning - a change in behavior resulting from exposure to new information.

But change your mind, say, about the general theory that you work with, at least in some fields, and you are looked upon as a kind of maverick, a person without proper research priorities, a pot-stirrer. Why is that, I wonder?

I think that the stigma against major mind changes in science results from what I call 'homeopathic bias' - scientific knowledge is built up bit by little bit as we move cumulatively towards the truth.

This bias can lead researchers to avoid concluding that their work undermines the dominant theory in any significant way. Non-homeopathic doses of criticism can be considered not merely inappropriate, but even arrogant - implying somehow that the researcher is superior to his or her colleagues, whose unifying conceptual scheme is now judged to be weaker than they have noticed or are been willing to concede.

So any scientist publishing an article or a book about a non-homeopathic mind-change could be committing a career-endangering act. But I love to read these kinds of books. They bother people. They bother me.

I changed my mind about this homeopathic bias. I think it is myopic for the most part. And I changed my mind on this because I changed my mind regarding the largest question of my field - where language comes from. This change taught me about the empirical issues that had led to my shift and about the forces that can hold science and scientists in check if we aren't aware of them.

I believed at one time that culture and language were largely independent. Yet there is a growing body of research that suggests the opposite - deep reflexes from culture are to be found in grammar.

But if culture can exercise major effects on grammar, then the theory I had committed most of my research career to - the theory that grammar is part of the human genome and that the variations in the grammars of the world's languages are largely insignificant, was dead wrong. There did not have to be a specific genetic capacity for grammar - the biological basis of grammar could also be the basis of gourmet cooking, of mathematical reasoning, and of medical advances - human reasoning.

Grammar had once seemed to me too complicated to derive from any general human cognitive properties. It appeared to cry out for a specialized component of the brain, or what some linguists call the language organ. But such an organ becomes implausible if we can show that it is not needed because there are other forces that can explain language as both ontogenetic and phlyogentic fact.

Many researchers have discussed the kinds of things that hunters and gatherers needed to talk about and how these influenced language evolution. Our ancestors had to talk about things and events, about relative quantities, and about the contents of the minds of their conspecifics, among other things. If you can't talk about things and what happens to them (events) or what they are like (states), you can't talk about anything. So all languages need verbs and nouns. But I have been convinced by the research of others, as well as my own, that if a language has these, then the basic skeleton of the grammar largely follows. The meanings of verbs require a certain number of nouns and those nouns plus the verb make simple sentences, ordered in logically restricted ways. Other permutations of this foundational grammar follow from culture, contextual prominence, and modification of nouns and verbs. There are other components to grammar, but not all that many. Put like this, as I began to see things, there really doesn't seem to be much need for grammar proper to be part of the human genome as it were. Perhaps there is even much less need for grammar as an independent entity than we might have once thought.